Let-off mechanism for looms



April 1, 1930 EQR. HOLMES 1,752,488

LET-OFF MECHANISM FOR LOOMS Y April l, 1930. E. R'. HOLMES LET-OFF MECHANISM FOR L'OOMS s sheets-sheet 2 Filed Dec. 6, 1927 April 1, 1930. E, R-HOLMES 1,752,488

I i LET-OFF MECHANISM FOR LOOMS Filed Deo.' 6, 1927 3 sheets-sheet s www *M Patented Apr. 1, 1930 UNITED STATES PATENT oFFICE ELBRIDGE R. HOLMES, OF WORCESTER, MASSACHUSETTS, ASSIGNOR T CROMPTON & KNOWLES LOOM WORKS, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS LET-OFF MECHANISM FOR LOOMS Application led December 6, 1927. Serial No. 238,151.

This invention relates to mechanism for letting off warp from the warp beam of a loom during the process'of weaving.

It is the general object of my invention to #iA provide an improved let-off mechanism for such purposes, by which uniform tension on the warp threads may be maintained and in which provision is made for readily adjusting the tension to correspond to the gradual 0 reduction in the diameter of the warp on the beam.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings in which- Fig. 1 is a side elevation of parts of a loom embodying my improvements;

Fig. 2 is a rear elevation thereof;

Fig. 3 is a plan view of parts of the mechanism, looking in the direction of the arrow 3 in Fig. 1; and

Figs. 4 and 5 are sectional detail rear elevations, taken respectively along the lines 4-4 and 5-5 in Fig. 1.

Referring to the drawings, I have shown a portion of a loom frame having a warp beam 11 (Fig. 2) rotatably mounted at the rear of said frame. The warp beam is provided with tbe usual beam heads 12 and has a rod or shaft 13 (Fig. 4) extending therethrough. A hub or cap 14 is provided for each end of the beam 11 and at the left hand end (as viewed in Figs. 2 and 4) a flanged collar 15 is also provided. A sprocket wheel 16 is riveted or otherwise secured to the flange of the collar 15.

The beam 11, hubs 14 andcollar 15 are all is itself freely rotatable in bearings 20 in the rear or swinging ends of levers 21 (Fig. 1) pivoted on studs 22 fixed in the loom frame 10.

A sleeve or bushing 25 (Fig. 2) is provided an adjusting rod 26 rotatable ina bracket 27 loosely mounted on a horizontal shaft 28, which in turn is rotatable in fixed bearings 29. Each threaded sleeve 25 is pivoted to swing transversely about a stud 30,.projectpreferably keyed to the rod or shaft 13, which' at each side of the loom, threaded to receiveV ing laterally from the side of its associated lever 21.

Each threaded rod 26 is secured in predetermined' verticalposition by a collar 32 thereon, engaging the upper end of its bearing 27 and by the hub 33 of a bevel gear 34 secured to each rod 26 below its bearing 27.

The gears 34 are engaged by pinions 35v on the shaft 28 previously described, and a wheel 37 (Fig. 1) is secured to the end of the shaft 28 and is provided with lugs or projections- 38 which may be engaged by the foot of the Weaver to turn the shaft 28 and thus change the vertical position of the warp beam. A latch or keeper 40 (Figs. 1 and 2)l is pivoted to one of the brackets 27 and normally holds the wheel 37 from rotation.

vWhen the shaft 28 is thus turned by the operator, the threaded rods 26 are simultaneously rotated and both ends of the beam are raised or lowered by equal amounts. It' is found desirable in the operation of the loom to keep the surface of the warp remaining on the warp beam substantially' at the level' of the breast beam 44 (Fig. 1) over which the cloth is drawn after weaving. By occasionally turning the wheel 37, the weaver is able to very easily maintain this approximately horizontal relation.,

Theleft hand lever 21 (Fig. 1)' has an upwardly projecting arm 45 connected by` a link 46 to a lever 47 pivoted'on a fixedbracket at 48 and connected at its' lower end by a linkv 49-to a member 50 (Fig. 3) in which is secured astud 51 for a roller 52.` A UV-shaped loop 53 is also mounted on thestud 51 and supports a headed rod 54 onY which tension weights 55 may be placed in any desired number.

The roller 52 rests upon the upper edge of a bell crank 56 pivoted on the stud 22 previously described and connected by a link 57 to a stud58 (Fig. 5') iiXed'in a lever 60 (Fig. 4) mounted to swing freely about thebeam shaft 13 between the ianged collarY 15 and the left hand supporting' lever 20. A stud 62 (Fig. 5) is fined in the lower end ofthe lever 60 and a. sprocket wheel 63 is loosely mounted on the stud62 and is connected by a chain 64 with the sprocket wheel 1G previously described.

A friction disc (Fig. 5) is keyed to the hub of the small sprocket wheel 63 and is engaged by friction rings 66 mounted on the adjacent faces of friction casing members 67, supported on the stud ($2 and hav' ig lugs G8 extending upwardly and embracing the laterally projecting end of the stud 5S previously described, whereby said casing members and friction rings are held from rotation.

The rear end of the stul G2 is provided with a steep pitch screw threaded meshing with corresponding thread; in the hub of an arm TO having a stud 7]. at its upper end, on which is pivoted a collar 72 loosely mouiited on the rear end of a link 73 1) the front end of said link being 1iivoted at T4 on a fixed bracket 75. A stop collar 'itl prevents rearward movement of the collar 72 which is pivoted on the arm itl and a col spring 77 on the link 78 yieldingly holds 'the collar 72 in engagement with the step collar 76. rIhe hub of the arm is adjacent the central portion of one of the friction casing members 67, a ball thrust bearing "itl being interposed between these parts. i

I'Iaving described the details of construction, I will now describe the operation of my improved let-off mechanism.

The shaft 28 is first adjusted by the foot of the operator to raise or lower the warp beam so that the warp will extend substantially horizontally from the upper surface of the warp beam 11 to the upper surface of the breast beam 4.4.

Assume that the friction rings G6 are firmly in engagement with the friction disc 65 and that for the time being they hold the disc 65 from rotation. As the cloth is woven, the Warp W' is pulled forward off of the warp beam and the beam necessarily rotates, carrying with it the sprocket wheel 16 fixed thereto.

As the sprocket 63 is fast with the disc 65 and is assumed to be held from rotation by the friction rings G6, the chain Gt forms praetically a rigid connection and swings the sprocket 63 and its supporting lever 60 rearward about the axis ofthe beam shaft 13. This action is resisted by the weights 55, acting through the bell crank 56 and link 57 on the lever GO, thus placing the desired tension on the Warp. The amount of this tension may be adjusted by varying the number of weights 55 and when once adjusted to a warp beam of a given diameter, the effect of the weights on the warp threads will be maintained substantially constant by the action of the link 46, the lever et? and link 49, which move the weight hanger 53 toward the stud .22 as the center of the warp shaft 13 is manually raised to offset the reduced diameter of the warp beam. As the warp beam grows smaller, the effective tension weight is thus reduced, maintaining a substantially constant rearward pull on the warp WV.

It will be evident, however, that the rearward swinging movement of the lever G0V would allow only a very short length of warp to be unwound from the warp beam 11 before the parts would be swung to an inoperative position. In order to maintain the parts in approximately their original and operative position, I have provided the friction disc 65 and friction rings 66 previously described, and the controlling arm 70 threaded on the stud G2 (Fig. 5).

As the threaded stud 62 in the lower end of the lever 60 is swung rearward by the acon of the sprocket chain 64E, the lower end of the friction arm 70 is correspondingly swung rearward, while the upper end of the arm 70 is held from such rearward movement by the stop collar 76.

rlhis causes anti-clockwise angular movement of the arm or lever 70 relative to the stud 62 and the stud is so threaded that this anti-clockwise movement causes the arm 70 to travel slightly outward on the stud (32, releasing the friction on the disc 65.

As soon as the friction is released, the weights 55 will act to swing the lever GO forward until the arm 70 is drawn inward by the stud 62 and reapplies locking friction to the disc 65. This cycle of operation is repeated at frequent intervals, the adjustment being entirely automatic and requiring no attention from the operator except to raise the axis of the warp beam from time to time to maintain the warp in a substantially horizontal position.

Any wear in the friction mechanism may be taken care of by angularly adjusting the threaded stud G2. The difference in diameter of the sprockets 1G and 63 increases the relative angular movement of the arm 70 and thus makes the device more sensitive. The ball thrust bearing 7S also contributes to the quick response of the mechanism to changes in warp tension.

Having thus described by invention andthe advantages thereof, I do not wish to be limited to the details herein disclosed otherwise than asset forth in the claims, but what I claim is 1. Loom let-off mechanism comprising a warp beam, means to tension the warp thereon, means to progressively raise said warp beam tranversely to the plane of delivery of the warp to maintain the warp threads substantially in a predetermined plane of delivery as the size of the warp beam is reduced, and means to simultaneously and progressively adjust the tension means as the warp beam is raised, thereby maintaining the warp tension substantially uniform.

2. Loom let-off mechanism comprising a warp beam, means to raise and lower said warp beam to maintain the warp threads substantially in a predetermined plane, a weight connected to tension the warp thereon, a supporting lever arm for said weight, and means to move said weight along said lever arm to vary the warp tension effectthereof as said warp beam is raised and lowered.

8. Loom let-off mechanism comprising a warp beam, means to raise and lower said warp beam to maintain the warp threads substantially in a predetermined plane, a weight connected to tension the warp thereon, and means to move said weight to automatically reduce the edective action thereof as the warp beam is raised manually to keep the warp threads in said predetermined plane, thereby maintaining the warp tension substantially uniform as the warp beam is reduced in diameter.

4. In a loom, a warp beam, means to apply tension thereto, manual means to progressively raise said warp beam transversely to the plane of delivery of the warp to maintain the warp threads substantially in a horizontal plane of delivery as the size of the warp beam is reduced, and automatic means to progressively vary the tension applied to said warp beam in acordance with the vertical position of said warp beam, thereby maintaining the warp tension substantially uniform.

5. In a loom, a loom frame, awarp bea-m, supporting arms for said warp beam pivoted to said loom frame and extending rearward therefrom, means to raise and lower said warp beam to maintain the warp threads substantially in a predetermined plane, a weight connected to tension the warp thereon, movable support therefor, and connections between one of said supporting arms and said weight by which the position of said weight on said support is changed as said warp beam is raised and lowered, 'thereby maintaining the warp tension substantially uniform.

6. In a loom, a warp beam rotatable by yarn tension thereon, a tension weight, connections etween said weight and said warp beam including a friction crevice, and means to release said friction device to allow automat-ic re-adjustment of said connections and thereby offset the rotation of the warp beam, while maintaining the tension thereon, said connections including a member movable with said warp beam and about the axis thereof as said warp beam rotates with said` friction device in operative position.

7. In a loom, a rotatably mounted warp beam, a tension weight, a connection between said weight and said warp beam, said connection including an arm depending from t-he axis of said warp beam but freely movable angularly relative thereto, a friction disc rotatably mounted on said depending' arm, friction members on said arm engaging said disc, and means to release sai-d friction members as said arm swings rearward and to restore the friction as said arm swings forward, whereby the annular relation of said arm to said warp beam may be carried while the warp tension is maintained thereon.

8. The combination in a loom as set forth in claim 7, in which said releasing means includes a stud fixed in the lower end of said arm and having a relatively steep pitch screw thread thereon, a releasing arm threaded on -said stud, and means to cause relative forward movement of said releasing arm as said depending arin is swung rearward.

9. rlhe combination in a loom as set forth in claim 7, in which said warp beam is connected to positively rotate said friction disc.

l0. The combination in a loom as set forth in claim 7, in which said warp beam is connected by sprockets and chain to positively rotate said friction disc, and in which the tension of the weightis applied through friction rings engaging said friction disc and releasable therefrom as said depending arm is swung rearward.

1l. In a loom, a warp beam, means to rotatably support said beam, a tension weight, connections between said weight and said warp beam including a depending arm freely swinging about the axis of said beam, a sprocket on said warp beam, a sprocket rotatably mounted at the lower end of said arm, a chain connecting said sprockets, a friction disc rotatable with said second sprocket, and means to release the friction and permit said second sprocket and friction disc to turn through a limited angle when said depending arm is moved rearward from normal position, and means to change the eifective leverage of said tensionweiffht to correspond substantially with the change in diameter of said warp beam.

In testimony whereof I have hereunto affixed my signature.

lELBRIDGE R. HOLMES. 

